Should you use air conditioning or open your windows? This is the EcoMinute and I’m ES.
Keeping windows open when traveling at highway speeds causes air drag, reducing your mileage by 10%. According to the Florida Department of Environmental Protection although auto air conditioners also reduce fuel economy, when driving over 40 mph, using the air conditioner uses less fuel than having open windows.
Keeping your sunroof open will also increase drag and decrease mileage. If the weather permits, the best option is to use your vents. Around town and at low driving speeds reduce air conditioner use. Additionally, park in the shade and leave your windows slightly open to reduce the need to cool your car.